ISSN:
0018-019X
Keywords:
Chemistry
;
Organic Chemistry
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Chemistry and Pharmacology
Notes:
(1)The third-order catalytic rate constants of the reaction of formaldehyde with urea with 5 general acid-base catalysts in aqueous solution were measured polarographically in the temperature range 30-45°.(2)The catalytic constants obtained with hydrogencarbonate, primary and secondary phosphate are higher than expected on the basis of the BRÖNSTED relationship. The activation entropies for the reactions with these catalysts are 15 to 20 entropy units lower than those with the water molecule and the hydroxyl ion as catalysts.(3)These observations indicate a bifunctional catalysis with a cyclic rate-determining transition state by the three firstmentioned catalysts. It is postulated that with mono- and bifunctional catalysts no termolecular collison step takes place, but first a hydrogen-bonded complex of the general acid catalyst with formaldehyde or the general base with urea is formed.
Additional Material:
1 Ill.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1002/hlca.19690520723
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